An important feature of small electronic devices is their display, which is often used to present a high-quality color image having limited dimensions at a low price. One of the ways to keep the physical dimensions of a pixel driver chip small (and thus to keep associated production costs low), and to keep power consumption low, is to decrease the amount of information that is used to describe the image. The decrease can be accomplished by reducing the number of bits used to describe each pixel, as well as by using advanced dithering algorithms that are used to try to make the reduction visually imperceptible.
A majority of the space on the pixel driver chip is typically occupied by a memory that is used to store image pixels. In many small electronic devices the image is stored as 18 bpp (bits per pixel), which is typically organized as six bits per pixel per color (bppc). Accordingly, when the number of the bits used to represent the image is reduced, the cost of the chip is also reduced.
The Human Visual System (HVS) is normally less sensitive to blue colors, so many imaging applications use half of the number of bits for the blue color channel that are used for other color channels. For example, color bit depths can be organized as a 5-5-2 bpp or 5-5-3 bpp scheme, which are used to represent red, green and blue pixels, respectively. However, in a display driver chip of conventional architecture, all of the color channels data are usually transferred using the same data bus. Accordingly, reduction in numbers of blue color plane bits does not necessarily further simplify the hardware, but instead usually adversely affects the image quality.